There are Gaussian interference channels in a wireless communication system. FIG. 1 illustrates Gaussian interference channels of two users. Such Gaussian interference channels may be naturally extended to interference channels of K users. Channels with mutual interference between multiple users are called interference channels. In FIG. 1, x1 and x2 represent signal transmitter, y1 and y2 represent corresponding remote signal receivers, solid arrows represent normal signal transmission, and dotted arrows represent interference that signals at a signal transmitter impose on remote receivers of other signal transmitters. As seen from FIG. 1, for transmit signals at an x1 point, transmit signals at an x2 point are interference sources; certainly, for transmit signals at the x2 point, transmit signals at the x1 point are also interference sources. That is, h12 and h21 are interference channels, resulting in that Tx1 imposes interference on Rx2 and that Tx2 imposes interference on Rx1. In the Gaussian interference channels, mutual interference exists between signals of different users; data cannot be shared between users and cannot be sent jointly, but each user knows a complete channel matrix.
Research shows that an interference alignment method may realize the degree of freedom of a Gaussian interference channel. The interference alignment means that when channel matrixes are already known, desired signals and interference signals at each receiver are separated spatially through preprocessing performed by the transmitters. One of the interference alignment methods in the prior art is as follows: at a receiver, interference from different transmitters is aligned with a space dimension, where the space dimension is different from a space dimension in which desired signals are located, so that interference on the desired signals is avoided. Another interference alignment method in the prior art is as follows: at a receiver, signals formed by superposing interference signals in receive signals filtered by receive vectors can form a lattice constellation pattern.
The inventor discovers that the prior art has at least the following problems: the prior art requires that all interference signals should be aligned in a same direction, where the direction is different from the direction in which desired signals are located; when the aligned interference is close to the desired signals in the space direction, the receiver cancels the interference, but the power of the desired signals becomes smaller and the signal-to-noise ratio of the desired signals at the receiver becomes lower, which makes it difficult to meet actual requirements; for the prior art, the current research shows that in an interference channel with more than two users, it is difficult to implement interference alignment by using a lattice construction method. That is, by using a single one of the two solutions in the prior art, the interference alignment of the multi-channel communication system can hardly achieve optimal performance.